Leverage. Tackling. Leverage. Tackling. Turns out Raiders head coach Jack Del Rio wasn’t saying those words only for his health.

His players got better at both and Del Rio has changed his tune the last month. He is even smiling more often. Through the season’s first eight games, Oakland was last in the NFL, allowing 314.6 net yards passing per game. In the past seven games, it is fifth at 210.4 per game.

“You praise it when it’s good,” Del Rio said. “You show examples of it being done properly. You get after guys when we’re not doing it as well … As coaches, we really like the idea that we feel like we can develop guys and help them be better, and we like praising guys.

“I think the guys have responded well to that.”

The Raiders have a chance to finish 8-8 with a win in Kansas City on Sunday. (And, no, Del Rio isn’t going to throw the game because the last two Oakland head coaches to finish 8-8, Tom Cable and Hue Jackson, were let go.)

Del Rio thinks his players have learned the importance of being “crisp” in all three phases of the game, and they have started to learn how to win.

“The bottom line is as long as you keep fighting, you have a chance,” Del Rio said. “You can keep yourself in games. I feel like we’ve done some of that with our defense here over the last month or month and a half where defensively, we’ve been in games.

“Earlier in the year, our offense was red hot and was carrying it, and the defense was having its struggles.”

The defense has picked itself up, even as it has lost important players along the way.

Defensive end Justin Tuck went down, linebacker Aldon Smith was suspended and then rookie defensive end Mario Edwards Jr. went down with a neck injury two weeks ago. The Raiders also lost rookie linebacker Neiron Ball to a knee injury, as well as top free-agent signing Nate Allen — the safety didn’t look good in his five games, but was also coming back from a Week 1 knee injury.

Benson Mayowa and Denico Autry thrived at defensive end in last Thursday’s win over San Diego. Mayowa recovered a fumble and his 40-yard runback set up a go-ahead touchdown. Autry had a sack and tackle for a loss.

“They are fighting,” Del Rio said. “I thought Denico was solid. Obviously, Benson had that big moment, that big return. Big Dan Williams and ‘Jelly’ (Justin Ellis). those two guys inside have been really tough for people to move. I think that’s been a real key for some of our effectiveness in the run front.”

Autry said the defensive line is extremely close.

“It’s a brotherhood,” Autry said. “Play together, step up for one another, eat together, go to each others’ houses, chill.”

And it’s clear they and the rest of the defense have heard what Del Rio, coordinator Ken Norton Jr. and the rest of the staff is preaching.

“We came together,” Autry said. “And we’re clearly playing better. Now let’s end it on a good note.”

Briefly: Raiders fullback Marcel Reece, suspended Monday for four games, said that he took a plant-root extract called Umcka, which he describes as a “completely safe substance that is clearly legal by NFL policy.” But an internal chemical reaction caused the positive test that led to his suspension by the NFL … Rookie receiver Amari Cooper sat out a good deal of last Thursday’s game because of a sore foot. He was asked if the extra rest bodes well for Sunday’s game. “Hopefully,” he said before practice. Cooper was limited in practice.